1. Field of the Invention
The present invention relates generally to an electromagnetic relay and, more particularly, to a complex electromagnetic relay including a plurality of relay structures, accommodated in a common housing, which are configured respectively as electromagnetic relays functionally independent of each other.
2. Description of the Related Art
There is known a complex electromagnetic relay including a plurality of relay structures accommodated in a single common housing in a side-by-side arrangement, wherein the respective relay structures are configured as electromagnetic relays functionally independent of each other and wherein each relay structure includes an electromagnet assembly and a contact section acting to open or close in accordance with the operation of the electromagnet assembly. This type of complex electromagnetic relay can be used in a control circuit frequently switching the operation of a motor or a solenoid between normal and reverse directions. Also, due to the provision of the common housing, the complex electromagnetic relay exhibits an effect of reducing a relay mount space, in comparison with a configuration using a plurality of electromagnetic relays having respective housings independent of each other, and, therefore, is effectively applicable to a control circuit where circuit components must be mounted in a narrow space, e.g., a control circuit for a vehicle-mounted electric-powered appliance such as a power window. particularly, a complex electromagnetic relay, in which a plurality of relay structures are configured as electromagnetic relays mechanically independent of each other in a common housing, makes it possible to control plural electric-powered appliances individually and in a timely fashion by a single complex electromagnetic relay, in contrast to another type of complex electromagnetic relay in which a pair of relay structures share a certain part of contact sections thereof with each other by, e.g., sharing a terminal member having a stationary terminal (i.e., a stationary contact member).
Japanese Unexamined patent publication (Kokai) No. 2003-59383 (JP-A-2003-59383) discloses a complex electromagnetic relay, in which plural (or a pair of) relay structures independent of each other are accommodated in a single housing so as to be oriented reversely to each other with the contact sections thereof being located alternately at opposing sides. In such an arrangement that the plural relay structures are placed to be inverted relative to each other as described in JP-A-2003-59383, coil-terminal pairs provided in the respective relay structures are arranged so as to protrude from the housing at positions spaced away from each other and, therefore, it is possible to advantageously facilitate the formation of a circuit pattern in an electromagnetic-relay mount board.
In the complex electromagnetic relay disclosed in JP-A-2003-59383, a pair of relay structures, each of which is configured as an independent electromagnetic relay, are mounted in a mutually inverted orientation onto a base block acting as a common holding member, and a box-like cover is attached to the base block so as to form the housing accommodating the relay structures. In this arrangement, problems may arise due to the presence of the base block, in that the dimension of the complex electromagnetic relay is increased especially in a height direction, and that the numbers of parts and of assembling steps are increased. Further, in this arrangement, it may be difficult to reduce the dimension of a housing while ensuring a desired insulation distance or clearance between the relay structures disposed side-by-side or, in particular, between armatures as actuating elements, in the respective electromagnet assemblies.